/Engine/Plugins/Media/PixelStreaming/Source/PixelStreamingInput/Public/IPixelStreamingInputHandler.h
TheIPixelStreamingInputHandler, used to handle input from a remote peer and pass it to UE accordingly. Setting the target viewport allows for scaling of input from browser to application, and setting the target window ensure that if windows are tiled (eg editor) that the streamed input only affect the target window.
class IPixelStreamingInputHandler : public [IInputDevice](API\Runtime\InputDevice\IInputDevice)
FOnSendMessage
OnSendMessage